Added @method annotations for view helpers

I have added @method annotations for all the builtin view helpers, so we can have IDE completion for the view helpers.
This is based on my [discussion](http://stackoverflow.com/questions/15138746/autocompletion-for-zf2-view-helpers-in-phpstorm) with Ocramius at StackOverflow. The same thing is already implemented in the [AbstractController](https://github.com/zendframework/zf2/blob/master/library/Zend/Mvc/Controller/AbstractController.php) for controller plugins.

I was not sure if I also need to add the translation view helpers which are located in the `zend_i18n` package. The `zend_view` component doesn't have a dependency on `zend_i18n` so that's why I left them out.